1. Field of the Invention
The present invention relates to a method and apparatus for enhancing night vision. More specifically the present invention relates to the use of a synchronization signal to adjust the gain on night-vision devices when the backlights of liquid crystal displays (LCDs) are being driven.
2. Problems in the Art
Airplane cockpits utilize LCDs to convey information to a pilot. Military pilots utilize night-vision goggles when flying their aircraft at night. The night-vision goggles allow the pilot to see things that he would not normally be able to see. Night-vision goggles greatly aid a pilot in finding targets at night.
Night-vision goggles operate by amplifying light. The gain or amplification of the goggles automatically varies with the amount of ambient light in the cockpit. In order to allow a pilot to receive maximum benefits from the goggles, it would be desirable to operate the goggles at maximum gain. However, because of the ambient light within the cockpit, which is primarily due to the light from the LCDs"" backlights, it is not possible to operate the goggles at a maximum gain. A decrease in the gain of the night-vision goggles makes objects outside of the cockpit more difficult to see. There is a need in the art for a device which minimizes the ambient light sensed by the goggles, allowing the goggles to operate at a higher gain for a longer time period. Such a device is disclosed by the present invention.
Currently optical filters are used to reduce the ambient light in the cockpit. The optical filters are placed on the LCD""s screen. These filters typically function by blocking out the frequency at which the night-vision goggles amplify. However, the spectrum at which night-vision goggles amplify is widening. Rather than having to cascade more filters or create more sophisticated filters, ambient light from LCDs can be nullified by synchronizing the backlights of LCDs with each other and with the gain on night-vision goggles. Optical filters would still be used to prevent light from leaving the cockpit, preventing other planes or people on the ground from seeing the cockpit light.
A primary feature of the present invention is a device and method that allows night-vision devices to operate at maximum gain for a greater period of time than previously allowed in the prior art.
Another feature of the present invention is the provision of a method and device which synchronizes LCD backlights with each other and with the gain on night-vision devices.
Another feature of the present invention is a method and device which effectively makes ambient light from LCD backlights xe2x80x9cinvisiblexe2x80x9d to night-vision devices.
Another feature of the present invention is a method and device which makes ambient light from light emitting diodes (LEDs) on the control panel xe2x80x9cinvisiblexe2x80x9d to night-vision devices.
Another feature of the present invention is a method and device which makes it easier for pilots to find targets at night.
These, as well as other features of the invention, will be apparent from the following description in conjunction with the accompanying drawings.
A method for enhancing the operation of a night-vision device involves synchronizing LCD backlights with each other and with the gain on the night vision device. A power source drives the backlights. When the backlights are being driven, the gain on the night vision device is reduced. Reducing the gain when the backlights are being driven eliminates most of the ambient light sensed by the night-vision device.
An apparatus for enhancing night-vision includes a night-vision device having a variable gain control, at least one LCD having a backlight, a power source to drive the backlight, and a synchronization signal source. The synchronization signal source is operatively connected to the power source and the variable gain control of the night-vision device. The synchronization signal controls driving of the backlight of the LCD. The synchronization signal also controls the gain of the night-vision device. When the synchronization signal causes the power source to drive the backlight, it also causes the gain of the night-vision device to decrease.